Invention Combines Features Of Keyboard, Fretless String Instrument

After nearly two decades of development and experimentation, the instrument -- a MIDI controller that gives performers continuous control over each note played -- is primed and ready for an international show-and-tell session. Haken, an adjunct professor of electrical and computer engineering at the University of Illinois and leader of the UI's CERL Sound Group, will demonstrate his invention at the International Computer Music Conference Aug. 28-Sept. 1 in Berlin.

The continuum fingerboard, which connects to a synthesizer or USB-capable computer, resembles a piano keyboard in shape and size, and, like a keyboard, is played with the fingers. However, it is more akin to a fretless string instrument in that it doesn't have discrete pitches.

"Any pitch may be played," said Haken, adding that the dynamics of the sound are controlled by finger pressure. "The front-to-back position of each finger affects timbre." Vibrato can be achieved by wiggling a finger on a particular spot on the instrument's surface, and glissando -- a smooth transition from one note to another -- also is possible.

"I've been interested in sound morphing for a long time," said the inventor, who hopes his instrument might be embraced by musicians and composers who create computer-generated music for a multitude of purposes ­ from advertising to film scores. "But I especially want to see it in live concert," said Haken, a lifelong fan of live music who knows his own way around a viola but humbly insists, "I play best with the door closed."

It may be a while before vast numbers of musicians start beating down Haken's door to acquire the continuum fingerboard. So far, only five full-sized models and two half-sized models have been manufactured. And Haken is the first to admit that his invention may not be the easiest instrument to learn to play. In part, that's because it doesn't have keys or other indicators to assist the musician in determining finger placement. The flat playing surface consists of a soft, red fabric that covers the mechanics of the instrument -- 256 rods, 5.75 inches long, mounted on piano-wire springs.

"The rods are covered by cloth so that the performer has the impression of a continuous surface rather than discrete keys," Haken said. "A magnet is mounted at both ends of each rod, and the rods are placed between two rows of Hall-effect sensors." The sensors measure the positions of the magnets, and when the performer applies pressure, rods under the finger are depressed and the magnets on those rods move closer to the sensors. Scanning software running on the instrument's internal computer then detects fingers by looking for any bar that has normalized sensor values greater than both of its neighboring bars.